import pandas as pd

data = {
    "Name": ["Alice", "Bob", "Tom", "Jerry", "David"],
    "Age": [22, 23, 24, 25, 26],
    "Source": [66, 99, 55, 77, 88],
    "City": ["Beijing", "Shanghai", "Guangzhou", "Shenzhen", "Hangzhou"],
}
df = pd.DataFrame(data)

age_max = df["Age"].max()
age_min = df["Age"].min()
source_sum = df["Source"].sum()
source_mean = df["Source"].mean()
print("age_max:", age_max)
print("age_min:", age_min)
print("source_sum:", source_sum)
print("source_mean:", source_mean)
""" 
age_max: 26
age_min: 22
source_sum: 385
source_mean: 77.0
"""